Method of forming pressed sheet metal spoked wheels



Oct. 22, 1935. J. MMLENNAN 2mm? METHOD OF FORMING PRESSED SHEET METAL SPOKED WHEELS Filed April 16, 1934 Patented Oct. 22, 1935 UNITED STATES PATENT OFFICE METHOD OF FORMING iiitEssEi) SHEET METAL SPOKED WHEELS Application April 16, 1934, Serial No. 720,873

3 Claims.

The invention relates to the manufacture of pressed sheet metal spoked vehicle wheels and more particularly to that type in which the spokes are of channel cross section having closed outer ends and merging at their inner ends into a dished annular portion with a reverse dished or cupped inner portion terminating in a radially inwardly extending bolting-on flange. It is the object of the invention to obtain a method for forming such a structure with such a distribution of drawing and compressive stresses as to avoid objectionable thinning or thickening of the metal in any portion. It is a further object to simplify and to reduce the number of operations required for completing the structure. With these objects in View the invention consists in the method as hereinafter set forth.

In the drawing:

Fig. 1 is a cross section of the original blank;

Fig. 2 is a similar view showing the first step of the cupping operation;

Fig. 3 is a similar view illustrating a succeeding cupping step;

Fig. 4 illustrates the bowling operation;

Fig. 5 shows the corrugating of portions of the bowl;

Fig. 6 is a cross section on line 6-6 of Fig. 5;

Fig. 7 is a cross section illustrating the radial corrugation of the bowl;

Fig. 8 is a plan view thereof.

Fig. 9 is a cross section through the wheel.

The wheel formed by my improved method is illustrated in Fig. 9 and comprises a cupped center portion A having a radially inwardly extending bolting-on flange B centrally apertured for engaging the wheel hub and provided with the usual bolt apertures C. Surrounding the portion A is a reversely dished portion D and projecting outward from this dished portion are spokes E of inwardly opening channel cross section and which terminate in closed ends F. The ends of the spokes fit within the rim G and are secured thereto preferably by rivets H passing through said rim and the closed spoke ends F.

To form this structure from pressed sheet metal and to accomplish the same with a fairly uniform distribution of drawing and compressive stresses, I proceed as follows: A circular blank I is centrally cupped by a series of successive operations as indicated at I, I Figs. 2 and 3, leaving an outwardly extending annular flange I in the original plane of the blank. The blank is next pressed between dies J and J to bowl the flange I in a reverse direction from the cupped portion I or so as to surround said cupped portion as shown in Fig. 4. The peripheral portion K of the bowl is substantially cylindrical and is of a diameter greater than the diameter of the finished spoked structure. In the next operation the blank is re-pressed between dies L and L' tocor- 5 rugate the portion intermediate the peripheral edge and the central cupped portion, as'indicated at M, Fig. 5, the deepest portion of the corrugations being shown in the cross section, Fig. 6, which is taken on the oblique line 6i3, Fig. 5. 10 This operation draws in the metal to reduce the radial dimension from the axis of the blank at the point of deepest corrugation and imparting to the bowl a flaring form. The blank is then re-pressed between dies N, N, Fig. 7, which are 15 fashioned to extend the corrugations to the periphery and to reduce the diameter of the latter. This imparts to the structure the form shown in Fig. 8 where the convex portions 0 of the corrugations form spokes separated by the concave 20 portions 0' and the ends of the convex portions being closed as indicated at 0 The corrugations M which form radially inward extensions of the corrugations O taper to merge into the surface of the bowl. roughly that of the finished center or spider of the wheel above described and may be brought into exact form and exact size by a re-striking or finishing die press operation.

It will be understood that to complete the 30 structure the cupped portion I must be pierced and fashioned to form the bolting-on flange but these operations do not form the subject matter of the present invention and are therefore not described in detail. 35

What I claim as my invention is:

Y 1. In a method of forming pressed sheet metal spoked wheels, the steps of cupping the central portion of a sheet metal blank leaving a surrounding annular portion in the original plane, 40 bowling the annular flange in a direction to surround said cup, corrugating the bowl thereby decreasing the diameter thereof, forming the convex portion of said corrugations into hollow spokes with closed ends and with the concave portions of the corrugations separating the spokes from each other.

2. In a method of forming pressed sheet metal spoked wheels, the steps of cupping the central portion of a sheet metal blank leaving a surrounding annular flange portion, bowling the annular flange in a direction to surround said cup, corrugating the bowl with the axis of the corrugations extending radially and at an oblique angle to the axis of the bowl, and further corru- Thus the form of the structure is 25' gating the peripheral portion of the bowl, thereby decreasing the diameter thereof, the convex portion of said corrugations forming hollow spokes with closed ends and the concave portion of the corrugations separating the spokes from each other.

3. In a method of forming pressed. sheet metal spoked wheels, thesteps of cupping the central portion of a sheet metal blank, leaving a surrounding annular flange portion, bowling the annular flange in 'a direction to surround said cup, the peripheral portion of the bowl being substantially parallel to the axis thereof with a rounded portion intermediate said peripheral portion and the cupped portion, corrugating the rounded portion of the bowl with the axis of the corrugations extending radially at an oblique angle to the axis of the bowl, further corrugating the peripheral portion of the bowl with the axis of the corrugations substantiallv'parallelto the axis of the bowl, the radially'projec'ting portions of said corrugations forming 'hollow spokes with 7 closed outer ends and the concave portions of the 10 corrugations forming open spaces between said spokes.

' JOHN MACLENNAN. 

